Optoelectronic properties of MoSe2 are modulated by controlled annealing in air.Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects.Considerable increase in electron and hole...Optoelectronic properties of MoSe2 are modulated by controlled annealing in air.Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects.Considerable increase in electron and hole mobilities reveals the highly improved electron and hole transport.Furthermore,the photocurrent is enhanced by nearly four orders of magnitudes under 7 nW laser exposure after annealing.The remarkable enhancement in the photoresponse is attributed to an increase in hole trapping centers and a reduction in resistance.Furthermore,the annealed photodetector shows a fast time response on the order of 10 ms and responsivity of 3×10^(4) A/W.展开更多
Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a d...Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a dynamic heterojunction-based direct current generator builds up new platforms for developing in situ energy.However,the requirement of different semiconductors in dynamic heterojunction is too complex to wide applications,generating energy loss for crystal structure mismatch.Herein,dynamic homojunction generators are explored,with the same semiconductor and majority carrier type.Systematic experiments reveal that the majority of carrier directional separation originates from the breaking symmetry between carrier distribution,leading to the rebounding effect of carriers by the interfacial electric field.Strikingly,NN Si homojunction with different Fermi levels can also output the electricity with higher current density than PP/PN homojunction,attributing to higher carrier mobility.The current density is as high as 214.0 A/m^(2),and internal impedance is as low as 3.6 kΩ,matching well with the impedance of electron components.Furthermore,the N-i-N structure is explored,whose output voltage can be further improved to 1.3V in the case of the N-Si/Al2O3/N-Si structure,attributing to the enhanced interfacial barrier.This approach provides a simple and feasible way of converting low-frequency disordered mechanical motion into electricity.展开更多
Surface charge transfer doping has been widely utilized to tune the electronic and optical properties of semiconductor photodetectors based on low-dimensional materials.Although many studies have been conducted on the...Surface charge transfer doping has been widely utilized to tune the electronic and optical properties of semiconductor photodetectors based on low-dimensional materials.Although many studies have been conducted on the performance(response time,responsivity,etc.)of doped photodetectors and their mechanisms,they merely examined a specific thickness and did not systematically explore the dependence of doping effects on the number of layers.This work performs a series of investigations on ReS_(2)photodetectors with different numbers of layers and demonstrates that the p-dopant tetrafluorotetracyanoquinodimethane(F_(4)-TCNQ)converts the deep trap states into recombination centers for few-layer ReS_(2)and induces a vertical p-n junction for thicker ReS_(2).A response time of 200 ms is observed in the decorated 2-layer ReS_(2)photodetector,more than two orders of magnitude faster than the response of the pristine photodetector,due to the disappearance of deep trap states.A current rectification ratio of 30 in the F_(4)-TCNQ-decorated sandwiched ReS_(2)device demonstrates the formation of a vertical p-n junction in a thicker ReS_(2)device.The responsivity is as high as 2,000 A/W owing to the strong carrier separation of the p-n junction.Different thicknesses of ReS_(2)enable switching of the prominent operating mechanism between transforming deep trap states into recombination centers and forming a vertical p-n junction.The thicknessdependent doping effect of a two-dimensional material serves as a new mechanism and provides a scheme toward improving the performance of other semiconductor devices,especially optical and electronic devices based on low-dimensional materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61904043)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ19A040009).
文摘Optoelectronic properties of MoSe2 are modulated by controlled annealing in air.Characterizations by Raman spectroscopy and XPS demonstrate the introduction of oxygen defects.Considerable increase in electron and hole mobilities reveals the highly improved electron and hole transport.Furthermore,the photocurrent is enhanced by nearly four orders of magnitudes under 7 nW laser exposure after annealing.The remarkable enhancement in the photoresponse is attributed to an increase in hole trapping centers and a reduction in resistance.Furthermore,the annealed photodetector shows a fast time response on the order of 10 ms and responsivity of 3×10^(4) A/W.
基金This work was funded by the National Natural Science Foundation of China(Nos.51202216,51502264,and 61774135)Special Foundation of Young Professor of Zhejiang University(No.2013QNA5007)Y.Wen thanks the support from the Science and Technology Project of Jiangsu Province Special Equipment Safety Supervision and Inspection Institute(KJY2017016).
文摘Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a dynamic heterojunction-based direct current generator builds up new platforms for developing in situ energy.However,the requirement of different semiconductors in dynamic heterojunction is too complex to wide applications,generating energy loss for crystal structure mismatch.Herein,dynamic homojunction generators are explored,with the same semiconductor and majority carrier type.Systematic experiments reveal that the majority of carrier directional separation originates from the breaking symmetry between carrier distribution,leading to the rebounding effect of carriers by the interfacial electric field.Strikingly,NN Si homojunction with different Fermi levels can also output the electricity with higher current density than PP/PN homojunction,attributing to higher carrier mobility.The current density is as high as 214.0 A/m^(2),and internal impedance is as low as 3.6 kΩ,matching well with the impedance of electron components.Furthermore,the N-i-N structure is explored,whose output voltage can be further improved to 1.3V in the case of the N-Si/Al2O3/N-Si structure,attributing to the enhanced interfacial barrier.This approach provides a simple and feasible way of converting low-frequency disordered mechanical motion into electricity.
基金This work was supported by the National Natural Science Foundation of China(No.61904043)the Natural Science Foundation of Zhejiang Province(No.LQ19A040009).
文摘Surface charge transfer doping has been widely utilized to tune the electronic and optical properties of semiconductor photodetectors based on low-dimensional materials.Although many studies have been conducted on the performance(response time,responsivity,etc.)of doped photodetectors and their mechanisms,they merely examined a specific thickness and did not systematically explore the dependence of doping effects on the number of layers.This work performs a series of investigations on ReS_(2)photodetectors with different numbers of layers and demonstrates that the p-dopant tetrafluorotetracyanoquinodimethane(F_(4)-TCNQ)converts the deep trap states into recombination centers for few-layer ReS_(2)and induces a vertical p-n junction for thicker ReS_(2).A response time of 200 ms is observed in the decorated 2-layer ReS_(2)photodetector,more than two orders of magnitude faster than the response of the pristine photodetector,due to the disappearance of deep trap states.A current rectification ratio of 30 in the F_(4)-TCNQ-decorated sandwiched ReS_(2)device demonstrates the formation of a vertical p-n junction in a thicker ReS_(2)device.The responsivity is as high as 2,000 A/W owing to the strong carrier separation of the p-n junction.Different thicknesses of ReS_(2)enable switching of the prominent operating mechanism between transforming deep trap states into recombination centers and forming a vertical p-n junction.The thicknessdependent doping effect of a two-dimensional material serves as a new mechanism and provides a scheme toward improving the performance of other semiconductor devices,especially optical and electronic devices based on low-dimensional materials.
